EMF

    activates ElectroMagnetic FLUKA: transport of electrons, positrons and
    photons

    See also DEFAULTS, DELTARAY, EMF-BIAS, EMFCUT, EMFFIX, EMFFLUO, EMFRAY,
    MULSOPT, PHOTONUC


     WHAT(1-6): not used

     
SDUM
 :    EMF-OFF to switch off electron and photon transport.
               Useful with the new defaults where EMF is on by default.

     
Default
: EMF on

     
Default
 (option EMF not requested): if option DEFAULTS is not used, or if
               it is used with 
SDUM
 = NEW-DEFAults, CALORIMEtry, EM-CASCAde,
               HADROTHErapy, ICARUS or PRECISIOn, electrons, positrons and
               photons are transported.
               If DEFAULTS is used with 
SDUM
 = EET/TRANsmut, NEUTRONS, SHIELDINg
               or anything else, electrons, positrons and photons are not
               transported (see Note 2). To avoid their energy to be deposited
               at the point of production, it is generally recommended to
               discard those particles (see Note 5).

     
Notes:
         1) Option EMF is used to request a detailed transport of electrons,
            positrons and photons. Even if the primary particles are not photons
            or electrons, photons are created in high-energy hadron cascades,
            mainly as a product of pi0 decay, but also during evaporation and
            fission of excited nuclei; and capture gamma-rays are generated
            during low-energy neutrons transport. Electrons can arise from muon
            decay or can be set in motion in knock-on collisions by charged
            particles (delta-rays).

         2) If EMF has been turned off by overriding the default (by setting
            
SDUM
 = EMF-OFF or by a DEFAULTS option which switches off
            electron-photon transport, such as EET/TRANsmut, NEUTRONS, 
            SHIELDINg, not accompanied by an explicit EMF request), such 
            electrons, positrons and photons are not transported and their
            energy is deposited on the spot at the point of creation unless
            those particles are DISCARDed (see Note 5 below).

         3) Of course, it is also mandatory to request option EMF (either
            explicitly or implicitly via option DEFAULTS) in any pure electron,
            positron or photon problem (i.e. with electrons, positrons or
            photons as primary particles).

         4) Using EMF without any biasing can lead to very large computing
            times, especially in problems of high primary energy or with low
            energy cutoffs. See in particular leading-particle biasing with
            EMF-BIAS.

         5) In case of a pure hadron or neutron problem (e.g. neutron activation
            calculation) it is recommended to DISCARD electrons, positrons and
            photons (id-number 3, 4 and 7). In this case it is irrelevant
            whether the EMF card is present or not. Discarding only electrons
            and positrons, but not photons, may also be useful in some cases
            (for instance when calculating photon streaming in a duct).

         6) An alternative is to set very large energy cutoffs for electrons
            and positrons (see EMFCUT). That will result in the electron energy
            being deposited at the point of photon interaction (kerma
            approximation, often sufficient for transport of photons having an
            energy lower than a few MeV).

         7) Hadron photoproduction is dealt with by option PHOTONUC.

     
Example:

 *....+....1....+....2....+....3....+....4....+....5....+....6....+....7...+...8
 EMF                                                                    EMF-OFF
 *   This command must be issued without any WHAT parameter.

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